An increase in food poisoning caused by Salmonella has been a problem recently. When Salmonella is classified by the serum type, the pathogenic bacteria consist mostly of Salmonella belonging to Groups O4, O7, and O9 among Salmonella. Thus, the great importance has been placed on the establishment of the method for specifically detecting Salmonella belonging to these groups.
As the detection of Salmonella, for example, a method using a selective medium is known. This method is a method in which Salmonella is detected by cultivating bacteria contained in a sample using a growth medium and thereafter selectively growing Salmonella in the cultivated bacteria using a selective medium (e.g., RV medium). Unfortunately, there is a problem in that not only Salmonella but also Citrobacter which is opportunistic pathogen and the like are grown in the selective medium, for example. Thus, the detection of Salmonella only by the presence or absence of the growth in the selective medium is not realistic, and the identification by the serum type using an antibody or the like is further required.
In addition, a method in which a sequence specific to Salmonella is amplified by a gene amplification method such as PCR, and Salmonella is detected by the presence or absence of the amplification has been proposed. Unfortunately, when a target sequence is specifically amplified in the gene amplification method, setting of amplification conditions such as designing of a sequence for primer and the like in order to avoid amplification of similar sequences is complicated Moreover, there is a problem in that time is required to perform the amplification reaction.
On the other hand, studies on a nucleic acid molecule (aptamer) which specifically binds to a target as a novel tool alternative to the antibody have been conducted. The aptamer has a lower molecular weight than the antibody. Thus, the aptamer is easily synthesized and can be modified and the like, and various applications utilizing binding between the aptamer and a target have been considered. As to the detection of Salmonella, an aptamer which binds to Salmonella has been reported (Non-Patent Document 1).